1. Field of Invention
The present invention relates generally to devices and systems capable of filtering and treating liquids. More specifically, the present invention relates to such devices and systems which are portable and which independently filter and treat cooking oil in fryers after the cooking process is interrupted.
Fryers are extensively used in the food industry to cook various comestibles. A common type of fryer includes a relatively deep container with the comestible to be cooked immersed in cooking oil in the container. The food industry utilizes substantial quantities of cooking oil in cooking fryers. Extending the usable life of cooking oil would substantially reduce the amount of money spent by the food industry on oil and would thus provide the industry a substantial economic benefit.
However, the cooking and heating processes continually alter and degrade the physical and chemical properties of cooking oil thereby reducing the useful life of the oil. Examples of contributors to the alteration and degradation of the cooking oil are food particles that become dislodged from the food during the cooking process and thereafter remain in the oil, water and fats that are extracted from the food during the cooking process and also remain in the oil thereafter, and free fatty acids that form when heat, water, and oxygen act upon and chemically alter the cooking oil and the comestibles (collectively referred to as "the contributors").
Food particles, if not removed from the cooking oil, will eventually become charred and will impart unwanted tastes, odors, and dark color to the oil. Free fatty acids contribute to the degradation of the cooking oil in that as the percentage of free fatty acids in the cooking oil increases, the smoke, flash, and fire points of the cooking oil are reduced. A large reduction in the smoke, flash, and fire points of the cooking oil may result in a fire hazard and/or may cause excessive smoke emissions. The presence of any of these contributors may, by itself, be cause to replace degraded, used oil with new oil.
In order to prolong the usable life of cooking oil, it is thus productive to neutralize and limit the presence and effects of the contributors by filtering the oil to remove the charred food particles and treating the oil to neutralize some of the chemical alterations generated by the contributors.
2. Related Art
In prior art systems, cooking oil is cleaned by pumping it through a filter assembly often containing filter paper or other disposable filter media. A filter powder is normally applied to the filter media by dispersal in the cooking oil. Filter powders commonly consist of diatomaceous earth, perlite or magnesium silicate. In the filtration process, filter powders form a coating on the surface of filter media and thereby mechanically strain suspended solids from liquids.
Such prior art filter powders may also include blends which treat the cooking oil upon contact. However, in order for the blends in the filter powder to sufficiently treat the cooking oil, a specific amount of filter powder and blend (per volume of cooking oil) must be introduced into the cooking oil. If an operator introduces an incorrect amount of filter powder and blend into the cooking oil, then the cooking oil will not be treated adequately.
Thus, the success of cooking oil treatment by such prior art methods depends at least in part on the measuring accuracy of the operator who introduces the filter powder into the cooking oil. It would therefore be a benefit to the industry to design an apparatus which provides adequate treatment of cooking oil in every instance by removing the potential of an operator measuring error. It would also be a benefit to the industry to design such an apparatus so that it is portable from one fryer to another.
In addition, in the majority of prior art systems, filtration takes place only after the cooking process is interrupted. This type of filtration is commonly known in the art as "intermittent" or "batch" filtration and is distinguished from continuous filtration which takes place while the cooking process is actuated. Generally, continuous filtration requires a specially designed fryer and filtration system. On the other hand, batch/intermittent filtration systems are normally capable of filtering the cooking oil in most fryers. It would thus be a benefit to the industry to design an apparatus as heretofore described which is capable of filtering the cooking oil in most fryers by batch/intermittent filtration.
This Applicant's U.S. Pat. No. 5,595,107 discloses a filtering and treating device including an external wire mesh filter screen, an inner, rigid, support or insert, and a centrally-disposed spool, the spool including fluid channels connectable to a suction pump. The shell and the interior walls define compartments to retain treating materials, such as activated carbon, which extend the usable life of the cooking oil. The suction pump draws liquid from outside the wire mesh envelope, through the support/insert, through the compartments and treating material and, through the central spool. Thus, the claimed device is capable of continuously and concurrently filtering and treating cooking oil during the cooking operation without the need for filter powders. However, the claimed devices are not portable and may not be used as a batch or intermittent filtration system capable of filtering the cooking oil in most existing fryers.
This Applicant's co-pending U.S. patent application Ser. No. 08/784,371, now U.S. Pat. No. 5,731,024 discloses a continuous and concurrent closed filtering and treating device, comprising a filtering mechanism immersed in a tank of liquid (fryer), a treating mechanism situated external to said tank, and a suction pump which draws liquid (cooking oil) from the reservoir through the filtering mechanism, through the treating mechanism, and pumps it back into the tank. The treating mechanism is a vessel in one embodiment and a container in another embodiment and is provided with an inlet and an outlet and a selectively removably attached top. Treating material is disposed within the treating mechanism. Cooking oil is pumped through the treating mechanism thereby contacting the treating material disposed within the treating mechanism. Treating material comprises any material, such as activated carbon, which upon contact with the cooking oil can extend the usable life of the cooking oil. Although the device eliminates the use of filter powders, the claimed device is not portable and cannot be used as a batch or intermittent filtration system capable of filtering the cooking oil in most fryers.
The prior art does not disclose a portable device which provides filtration and treatment of the cooking oil, eliminates the need for filter powder, and can be used as a batch or intermittent filtration system capable of filtering the cooking oil in most fryers.